JP4132771B2

JP4132771B2 - Biological reaction tank and stirring method thereof

Info

Publication number: JP4132771B2
Application number: JP2001315323A
Authority: JP
Inventors: 幸弘二星; 信之井上
Original assignee: Kobelco Eco Solutions Co Ltd
Current assignee: Shinko Pantec Co Ltd
Priority date: 2001-10-12
Filing date: 2001-10-12
Publication date: 2008-08-13
Anticipated expiration: 2021-10-12
Also published as: JP2003117583A

Description

【０００１】
【発明の属する技術分野】
本発明は、嫌気性微生物を用いて下水、排水等の汚水を浄化処理する生物反応槽およびその攪拌方法の改善に係り、より詳しくは、嫌気槽または無酸素槽内の汚水の酸素状態を適正範囲に維持しながら、長期間安定して汚水を十分に攪拌することを可能ならしめるようにした生物反応槽およびその攪拌方法の技術分野に属するものである。
【０００２】
【従来の技術】
下水、排水等の汚水中の燐除去に用いられる嫌気−好気活性汚泥法は、標準活性汚泥法の一変形で、これはＢＯＤ(生物化学的酸素要求量)、燐の同時除去、およびバルキング(糸状性細菌の増殖で活性汚泥が膨張して沈降し難くなる現象)の防止に有効とされているプロセスである。このような従来技術としては、例えば特開平７−３２８６８８号公報に開示されてなる「嫌気性汚水処理方法及びその装置」や、特許第２９８４５７９号公報に開示されてなる「生物反応槽」が公知である。
【０００３】
先ず、特開平７−３２８６８８号公報に開示されてなる従来例１を、嫌気性汚水処理装置の概略断面図の図７を参照しながら、同公報に記載されている同一名称ならびに同一符号を以って説明すると、嫌気性汚水処理装置１は、その本体が処理槽２からなり、図示しないポンプによって送水された生活排水等の被処理水は、マンホール３から処理槽２内に流入する。そして、嫌気性微生物によって処理された後、処理槽２の上部断面に開口する放流口４から放流される。処理槽２内に堆積した汚泥は、処理槽２の上部から蛇腹ホースによる吸引により排出されるようになっている。処理層２の下部には、エアー供給装置６からエアー供給管７を介してエアーが供給される散気装置５が配設されており、この散気装置５から放出されるエアーによって槽内が攪拌されるようになっている。
【０００４】
散気装置５には、３０〜１２０分間に１回だけ１〜６０秒間エアーが供給されるようになっている。このような時間は、処理槽２の大きさ、汚水の質、エアー供給量等によって相違するが、嫌気性微生物を不活性状態にしない程度でＢＯＤ、ＣＯＤ、全窒素分の除去率が高くなるように適宜調整される。また、エアー量が少ないと汚泥の攪拌効果が十分でなく、一方エアー量が多いと嫌気処理にならないので、供給するエアー量としては、その酸素量が０．５〜１０ｇ／ｍ^３分であることが好ましいとしている。
【０００５】
次に、特許第２９８４５７９号公報に開示されてなる従来例２を、生物反応槽の模式的構成説明図の図８を参照しながら、同公報に記載されている同一名称ならびに同一符号を以って説明すると、生物反応槽１を嫌気槽２と好気槽４とからなる構成とし、嫌気槽２の底部に１００〜１０００ｍｍのピッチで２〜８ｍｍ径の複数の気孔を有する粗大気泡散気装置５を配設する。また、好気槽４の底部に２６０μｍの微細気孔を有する微細気泡散気板６を配設した構成になるものである。そして、粗大気泡散気装置５には１槽あたり０．７ｍ^３／分の空気量が、また微細気泡散気板６には０．４ｍ^３／分の空気量が供給される。
【０００６】
【発明が解決しようとする課題】
上記従来例１に係る「嫌気性汚水処理方法およびその装置」、または上記従来例２に係る「生物反応槽」によれば、汚水を浄化処理することができるのでそれなりに有用であるが、それぞれ後述するような解決すべき課題がある。
【０００７】
先ず、上記従来例１では、処理槽２内に０．５〜１０ｇ／ｍ^３分の量の酸素が送気されるが、この酸素量は、１．８〜３５．８リットル／ｍ^３分(２０℃)の空気量に相当する。本願出願人の実験によれば、空気量は１．４リットル／ｍ^３分が適切であるという結果が得られ、この従来例１に係る空気量の範囲は必ずしも適切ではない。この従来例１に係る散気装置５は、処理槽２の底部に配設されているが、槽の形状によっては汚水を十分に攪拌することができない。
【０００８】
上記従来例２では、嫌気槽２の底部に１００〜１０００ｍｍのピッチで２〜８ｍｍ径の複数の気孔を有する粗大気泡散気装置５が配設されているが、空気放出停止時に気孔から粗大気泡散気装置５に汚水が逆流したりするので空気の送気に支障が生じ、汚水を十分に攪拌することができなくなる恐れがある。
【０００９】
従って、本発明は、嫌気槽または無酸素槽内の汚水の酸素状態を適正範囲に維持しながら、長期間安定して汚水を十分に攪拌することを可能ならしめる生物反応槽およびその攪拌方法を提供することである。
【００１０】
【課題を解決するための手段】
本発明は、上記実情に鑑みてなされたものであって、従って上記課題を解決するために、本発明の請求項１に係る生物反応槽が採用した手段の特徴とするところは、嫌気槽または無酸素槽内に流入する下水、排水等の汚水を、これら嫌気槽または無酸素槽内に設けられた散気装置からの気泡の放出により攪拌しながら浄化処理する生物反応槽において、前記散気装置は、前記嫌気槽または無酸素槽内に配設されてなる１以上の送気管と、これら送気管のそれぞれに所定のピッチで配設された複数のディフューザとから構成されてなり、前記ディフューザは、前記送気管に接続され、中心部に空気流路を有する送気筒と、この送気筒の上部に外嵌され、外周部に複数の気孔を有すると共に、上部に傘部を有するクラウンと、このクラウンの内部空間の上部に収容され、前記空気流路からの空気の流入により浮き上がり、クラウンの内部空間側に開口する空気流路の上部開口部の遮断を開放する一方、空気の送気停止時には下降して前記上部開口部を遮断するブロック状の弁体とからなるところにある。
【００１１】
本発明の請求項２に係る生物反応槽が採用した手段の特徴とするところは、請求項１に記載の生物反応槽において、前記送気管は、前記嫌気槽または無酸素槽の１内壁側の偏った位置に配管されてなるところにある。
【００１２】
本発明の請求項３に係る生物反応槽が採用した手段の特徴とするところは、請求項２に記載の生物反応槽において、前記嫌気槽または無酸素槽の水深中間位置に、前記送気管が配管されると共に、前記嫌気槽または無酸素の送気管配設側の１内壁側と他内壁側とを隔て、これら１内壁側と他内壁側との間で汚水を循環させる整流板が配設されてなるところにある。
【００１３】
本発明の請求項４に係る生物反応槽の攪拌方法が採用した手段の特徴とするところは、嫌気槽または無酸素槽内に流入する下水、排水等の汚水を浄化処理するために、前記嫌気槽または無酸素槽内に設けられたディフューザの気孔から粗大気泡を間欠的に放出して前記汚水を攪拌する生物反応槽の攪拌方法であって、前記送気管から前記ディフューザに空気を送気しているときには前記送気管から気孔に通じる空気流路を開放して前記複数の気孔から粗大気泡を放出し、放出した粗大気泡を前記気孔の上部の傘部の下面に沿って外方に広がらせると共に、空気の送気停止時には前記空気流路を遮断するところにある。
【００１４】
【発明の実施の形態】
以下、本発明の生物反応槽の攪拌方法を実施する実施の形態１に係る生物反応槽を、模式的に示すその側面断面図の図１(ａ)と、好気槽側から見た嫌気槽の横断断面図の図１(ｂ)と、粗大気泡散気装置を構成するディフューザの外形図の図１(ｃ)と、粗大気泡放出状態を示すディフューザの半部断面示構成説明図の図２(ａ)と、送気停止状態を示すディフューザの半部断面示構成説明図の図２(ｂ)とを順次参照しながら説明する。
【００１５】
図１(ａ)に示す符号１は、下水、排水等の汚水を微生物により浄化処理する生物反応槽であって、この生物反応槽１は、沈殿池１０から下水、排水等の汚水が流入すると共に、図示しない最終沈殿池から汚泥が返送される嫌気槽または無酸素槽(以下、嫌気槽という。)２と、この嫌気槽２で処理された処理水が流入する好気槽３とから構成されており、嫌気・好気活性汚泥法により汚水を浄化処理するものである。前記嫌気槽２は水深６ｍ以内の汚水を流入させる深さのもので、その底部付近であって、かつ１内壁側の偏った位置に、図１(ｂ)に示すように、粗大気泡散気装置４が設けられている。このように、この粗大気泡散気装置４を嫌気槽２の１内壁側の偏った位置に配設することにより、嫌気槽２の１内壁側から粗大気泡が上昇するので、１内壁側の汚水は上昇流となり、水面付近で水平流となると共に、他壁側で下降流となるので、汚水は効果的に攪拌される。
【００１６】
前記粗大気泡散気装置４は、嫌気槽２の上部に配管された送気元管４３、およびこの送気元管４３から分岐し、嫌気槽２の内壁に沿って配管された送気分岐管４２ａを介し、この送気分岐管４２ａの分岐部付近に介装されてなる自動開閉弁４４の開閉により間欠的に空気が送気され、前記嫌気層２の底面の近傍に、この底面と平行に配置された送気管４２ｂと、この送気管４２ｂに所定のピッチで配設され、嫌気槽２内の汚水中に粗大気泡４５を放出するディフューザ４１とから構成されている。なお、前記送気元管４３には、図示しない送風機から空気が送気されるものである。
【００１７】
前記ディフューザ４１は、例えば図１(ｃ)に示すような外形になるもので、１ｍｍ以上の大きさの気孔を有すると共に、送気中は空気の流路が確保され、送気停止時は空気の流路が遮断されるように構成されていて、送気停止時に前記送気管４２内への汚水の逆流を阻止する機能を備えている。このディフューザ４１の具体的な内部構成は、図２(ａ)，(ｂ)に示すように、前記送気管４２ｂに接続され、中心部に空気流路４１ｂを有する送気筒４１ａと、この送気筒４１ａの上部に外嵌され、外周部に複数の気孔４１ｄを有するクラウン４１ｃと、このクラウン４１ｃの内部空間の上部に収容され、前記空気流路４１ｂからの空気の流入により浮き上がり、クラウン４１ｃの内部空間側に開口する空気流路４１ｂの上部開口部の遮断を開放する一方、空気の送気停止時には下降して前記上部開口部を遮断するブロック状の弁体４１ｅとから構成されている。
【００１８】
従って、前記ディフューザ４１によれば、空気の送気時には空気は、図２(ａ)において破線矢印で示すように、空気流路４１ｂ、この空気流路４１ｂの上部開口部と弁体４１ｅとの間を通ってクラウン４１ｃの内部空間に流入し、次いでクラウン４１ｃの外周部に設けられている気孔４１ｄから粗大気泡４５として流出し、クラウン４１ｃの傘部の下面に沿って外方に広がると共に嫌気槽２内の汚水中に放出されて上昇する。一方、空気の送気停止時には、図２(ｂ)において実線矢印で示すように、汚水は気孔４１ｄからクラウン４１ｃの内部空間内に流入するが、弁体４１ｅにより空気流路４１ｂの上部開口部が遮断されていて空気流路４１ｂに流入することがないので、送気管４２ｂへの汚水の流入が阻止されることとなる。
【００１９】
前記好気槽３は水深６ｍ以内の汚水を流入させる深さのもので、その底部付近に、送気管５２と、この送気管５２に所定のピッチで配設され、好気槽３の横断断面のほぼ全域に渡って微細気泡を放出する散気板５１とからなる微細気泡散気装置５が配設されている。この好気槽３は、前記嫌気槽２と異なり、酸素の溶解を促進させ、好気槽３内の汚水の溶存酸素を１．５ｍｇ／リットル以上に保持する必要があるので、この散気板５１には微細気泡を放出する１５０〜４００μｍの径の気孔が複数設けられている。この散気板５１の気孔からの微細気泡の放出により、酸素の溶解を促進させて汚水の好気状態を維持しながら、汚水を攪拌することができる。
【００２０】
以下、本実施の形態１に係る生物反応槽１の作用態様を説明すると、粗大気泡散気装置４それぞれのディフューザ４１の気孔４１ｄから嫌気槽２内の汚水中に、１．０〜３．０リットル／ｍ^３分の空気が粗大気泡４５として、５５分経過毎に５分間放出される。これらディフューザ４１のそれぞれは、上記のとおり、前記送気管４２ｂ内への汚水の逆流を阻止する機能を備えているために、従来例２に係る生物反応槽のように、空気の送気停止中でも送気管４２ｂ内に汚水が逆流したりするようなことがない。
【００２１】
従って、本実施の形態１に係る生物反応槽１によれば、支障なく空気溶解効率の低い粗大気泡４５を放出することができ、この粗大気泡４５の上昇により嫌気槽２内の汚水を効果的に攪拌することができる。また、従来例１よりも少量の送気量で良いため、嫌気槽２内の汚水の嫌気状態を容易に維持することができる。因みに、この嫌気槽２内の汚水のＤＯ(溶存酸素)は約０ｍｇ／リットルであり、またＯＲＰ(酸化還元電位)は−３００〜−２００ｍＶであって、嫌気状態が保持されていることを確認した。
【００２２】
なお、上記従来例１に係る嫌気性汚水処理装置の問題点として、送気する空気量１．８〜３５．８リットル／ｍ^３分(２０℃)は必ずしも適切でなく、１．４リットル／ｍ^３分が適切な空気量であると述べた。それにもかかわらず、この実施の形態１に係る生物反応槽１において、送気する空気量の範囲を１．０〜３．０リットル／ｍ^３分としたのは、嫌気槽２の形状や嫌気槽２内の汚泥混合濃度等の条件が相違していたとしても、汚水を確実に、かつ十分攪拌することができ、しかも嫌気性微生物の繁殖を妨げない嫌気状態を確実に維持することができたからである。また、本実施の形態１に係る生物反応槽１においては、空気は粗大気泡４５として、例えば５５分経過毎に５分間放出されるが、この放出時間も嫌気槽２の形状や嫌気槽２内の汚泥混合濃度等の条件によって相違するから、これらの時間は条件に応じて適宜変更されて然るべきものである。
【００２３】
ところで、攪拌装置として用いる粗大気泡散気装置４は、微細気泡散気装置５に比較して安価であり、送気管４２内に汚水が逆流しないから、攪拌装置として微細気泡散気装置を用いる場合に比較して生物反応槽の製造コストに関して経済的に有利になるのに加えて、その維持管理コストやランニングコストに関して有利になるという効果もある。
【００２４】
本発明の実施の形態２に係る生物反応槽を、模式的に示すその側面断面図の図３を参照しながら説明する。但し、本実施の形態２に係る生物反応槽が、上記実施の形態１に係る生物反応槽と相違するところは循環水管の有無にあり、それ以外は全く同構成であるから、同一のもの並びに同一機能を有するものに同一符号を付して、その相違する点について説明する。
【００２５】
即ち、本実施の形態２に係る生物反応槽１は、上記実施の形態１と同様に、嫌気槽２と好気槽３とを備えている。そして、前記嫌気槽２には前記好気槽３から、この好気槽３で処理された処理水の一部を循環させる循環水管６が連通してなる構成になっている。
【００２６】
従って、本実施の形態２に係る生物反応槽１によれば、循環式硝化脱窒法により汚水が浄化されるが、上記のとおり、上記実施の形態１に循環管６が付加されているだけだから、本実施の形態２に係る生物反応槽は上記実施の形態１に係る生物反応槽と同様に、嫌気槽２内の酸素状態を適正範囲に維持しながら攪拌することができるという効果がある。
【００２７】
本発明の実施の形態３に係る生物反応槽を、模式的に示すその側面断面図の図４を参照しながら説明する。但し、本実施の形態３に係る生物反応槽が、上記実施の形態１に係る生物反応槽と相違するところは、槽の構成と循環水管の有無にあり、それ以外は同構成であるから、同一のもの並びに同一機能を有するものに同一符号を付して、その相違する点について説明する。
【００２８】
即ち、本実施の形態３に係る生物反応槽１は、上記実施の形態１と同様に、嫌気槽２と好気槽３とを備えている。前記嫌気槽２は、水深６ｍ以内の汚水を流入させる深さのもので、その底部付近であって、かつ１内壁側の偏った位置に粗大気泡散気装置４が設けられ、図示しない最初沈殿池から一次処理された下水、排水等の汚水が流入すると共に、図示しない最終沈殿池から汚泥が返送される第１嫌気槽２１と、この第１嫌気槽２１で処理された処理水が流入する第２嫌気槽２２とからなっている。そして、この第２嫌気槽２２に前記好気槽３から、この好気槽３で処理された処理水の一部を循環させる循環水管６が連通してなる構成になっている。
【００２９】
従って、本実施の形態３に係る生物反応槽１によれば、嫌気・無酸素・好気法によって汚水が浄化処理されるが、上記のとおり、嫌気槽２が第１嫌気槽２１と第２嫌気槽２２とに２分割されている点と、循環水管６が設けられている点とにあり、それ以外は上記実施の形態１に係る生物反応槽と同構成であるから、本実施の形態３に係る生物反応槽は上記実施の形態１に係る生物反応槽と同様に、嫌気槽２内の酸素状態を適正範囲に維持しながら攪拌することができるという効果がある。
【００３０】
本発明の実施の形態４に係る生物反応槽を、模式的に示す２段構えのその側面断面図の図５(ａ)と、模式的に示す３段構えのその側面断面図の図５(ｂ)とを参照しながら説明する。但し、本実施の形態４に係る生物反応槽が、上記実施の形態１に係る生物反応槽と相違するところは、槽の構成と循環水管の有無にあり、それ以外は同構成であるから、同一のもの並びに同一機能を有するものに同一符号を付して、その相違する点について説明する。
【００３１】
本実施の形態４は、ステップ流入式多段脱窒化法で汚水を浄化処理するものであって、図５(ａ)に示す生物反応槽１は、嫌気槽２と好気槽３とからなる前段部分と、この前段部分の下流側に設けられ、嫌気槽２と好気槽３とからなる後段部分の2段構えに構成されている。そして、前記後段部分の嫌気槽２に、この後段部分の好気槽３から、この好気槽３で浄化処理された処理水の一部を循環させる循環水管６が連通している。
【００３２】
図５(ｂ)に示す生物反応槽１は、嫌気槽２と好気槽３とからなる前段部分と、この前段部分の下流側に設けられ、嫌気槽２と好気槽３とからなる中段部分と、この中段部分の下流側に設けられ、嫌気槽２と好気槽３とからなる後段部分の３段構えに構成されている。そして、前記後段部分の嫌気槽２に、この後段部分の好気槽３から、この好気槽３で浄化処理された処理水の一部を循環させる循環水管６が連通している。
【００３３】
本実施の形態４に係る生物反応槽１によれば、嫌気槽２と好気槽３とが交互に配設されると共に、後段部分の好気槽３から嫌気槽２に、この好気槽３で浄化処理された処理水の一部を循環させる循環水管６が連通しているだけだから、本実施の形態４に係る生物反応槽１は上記実施の形態１に係る生物反応槽１と同様に、嫌気槽２内の酸素状態を適正範囲に維持しながら攪拌することができるという効果がある。
【００３４】
本発明の実施の形態５に係る生物反応槽を、模式的に示すその側面断面図の図６(ａ)と、好気槽側から見た嫌気槽の横断断面図の図６(ｂ)とを参照しながら説明する。但し、本実施の形態５に係る生物反応槽が上記実施の形態１に係る生物反応槽と相違するところは、嫌気槽と好気槽との深さの相違にあり、それ以外は同構成であるから、同一のもの並びに同一機能を有するものに同一符号を付して説明する。
【００３５】
図６(ａ)に示す符号１は、生物反応槽であって、この生物反応槽１は嫌気槽２と、この嫌気槽２で処理された処理水が流入する好気槽３とから構成されており、前記嫌気槽２と好気槽３とは、共に水深６ｍを超える深さになっている。前記嫌気槽２の水深中間位置で、かつ１内壁側の偏った位置に、図６(ｂ)に示すように、底面と平行に配設されてなる送気管４２ｂと、この送気管４２ｂに所定のピッチで配設されてなるディフューザ４１とからなる粗大気泡散気装置４が設けられている。さらに、この粗大気泡散気装置４配設側の１内壁側と他内壁側とを隔て、前記粗大気泡散気装置４よりも上方位置まで延び、かつ嫌気槽２の底部付近の下方位置まで延びる整流板７が配設されている。
【００３６】
前記整流板７の働きにより、前記粗大気泡散気装置４が水深中間位置に配設されているにもかかわらず、粗大気泡４５の放出により生じる汚水の上昇流が整流板７の上端を超えると下降流となり、そして整流板７の下端と嫌気槽２の底面との間を流れると共に上昇流となって対流するので、嫌気槽２内の汚水の全体が効果的に攪拌される。
【００３７】
前記好気槽３の水深は、上記のとおり、６ｍを超える深さになっており、前記嫌気槽２と同様に、水深中間位置で、かつ１内壁側の偏った位置に、底面と平行に配設されてなる送気管５２と、この送気管５２に所定のピッチで配設され、微細気泡を放出する散気板５１とからなる微細気泡散気装置４が配設されている。さらに、この微細気泡散気装置５配設側の１内壁側と他内壁側とを隔て、前記微細気泡散気装置５よりも上方位置まで延び、かつ好気槽３の底部付近の下方位置まで延びる整流板７′が配設されている。この好気槽３においても、前記嫌気槽２と同様、整流板７′の働きにより、好気槽３内の汚水の全体が効果的に攪拌され、適正範囲の好気状態に維持される。
【００３８】
本実施の形態５に係る生物反応槽１によれば、嫌気槽２と好気槽３との深さが上記実施の形態１に係る生物反応槽と相違するだけで、そして整流板７の働きにより、嫌気槽２内の汚水を効果的に対流させて攪拌することができるので、上記実施の形態１に係る生物反応槽と同等の効果がある。さらに、この効果に加えて、嫌気槽２の水深が深いにもかかわらず、粗大気泡散気装置４が水深中間の浅い位置に配設されていて、空気の送気圧を低圧にすることができる。つまり、送風機の動力エネルギーを削減することができるから、生物反応槽１のランニングコストの低減に寄与することができる。
【００３９】
ところで、本実施の形態５に係る生物反応槽１においては、嫌気・好気活性汚泥法により汚水を浄化処理する、図１(ａ)に示す嫌気槽２と好気槽３とからなる構成の場合を例として説明したが、これら嫌気槽２と好気槽３とが図３乃至図５(ａ)，(ｂ)に示す何れの配設構成になる生物反応槽に対しても、本実施の形態５に係る生物反応槽１の技術的思想を適用することができ、また６ｍ以内の水深の嫌気槽２に対しても、粗大気泡散気装置５と遮蔽板７とを配設することにより、汚水を効果的に攪拌するという所期の目的を達成することができるので、嫌気槽２の水深に限定されるものではない。
【００４０】
【発明の効果】
以上述べたように、本発明の請求項１乃至３に係る生物反応槽または本発明の請求項４に係る生物反応槽の攪拌方法によれば、嫌気槽または無酸素槽内に設けられたディフューザは送気管内への汚水の逆流を阻止する機能を備えていて、従来例２に係る生物反応槽のように、空気の送気停止中でも送気管内に汚水が逆流するようなことがないから、支障なく空気溶解効率の低い粗大気泡を放出することができ、この粗大気泡により嫌気槽内の汚水を対流させて、効果的に攪拌することができる。また、従来例１に係る嫌気性汚水処理装置の場合よりも少量の空気量で良いため、嫌気槽内の汚水の嫌気状態を容易に維持することができるという優れた効果がある。
【００４１】
また、本発明の請求項１乃至３に係る生物反応槽によれば、攪拌装置として用いる粗大気泡散気装置は、微細気泡散気装置に比較して安価である。従って、攪拌装置として微細気泡散気装置を用いる場合に比較して生物反応槽の製造コストに関して経済的に有利になるのに加えて、その維持管理コストやランニングコストに関して有利になるという効果もある。
【００４２】
さらに、本発明の請求項３に係る生物反応槽によれば、嫌気槽または無酸素槽の水深中間位置に配設された送気管にディフューザが配設され、前記嫌気槽または無酸素の送気管配設側の１内壁側と他内壁側とを隔てる整流板が配設されているので、上記効果があるのに加えて、空気の送気圧を低圧にすることができ、送気するための動力エネルギーを削減することができるから、生物反応槽のランニングコストの低減に寄与することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１に係り、図１(ａ)は模式的に示す生物反応槽の側面断面図、図１(ｂ)は好気槽側から見た嫌気槽の横断断面図、図１(ｃ)は粗大気泡散気装置を構成するディフューザの外形図である。
【図２】本発明の実施の形態１に係り、図２(ａ)は粗大気泡放出状態を示すディフューザの半部断面示構成説明図、図２(ｂ)は送気停止状態を示すディフューザの半部断面示構成説明図である。
【図３】本発明の実施の形態２に係り、模式的に示す生物反応槽の側面断面図である。
【図４】本発明の実施の形態３に係り、模式的に示す生物反応槽の側面断面図である。
【図５】本発明の実施の形態４に係り、図５(ａ)は模式的に示す２段構えの生物反応槽の側面断面図、図５(ｂ)は模式的に示す３段構えの生物反応槽の側面断面図である。
【図６】本発明の実施の形態５に係り、図６(ａ)は模式的に示す生物反応槽の側面断面図、図６(ｂ)は好気槽側から見た嫌気槽の横断断面図である。
【図７】従来例１に係る嫌気性汚水処理装置の概略断面図である。
【図８】従来例２に係る生物反応槽の模式的構成説明図である。
【符号の説明】
１…生物反応槽
２…嫌気槽または無酸素槽、２１…第１嫌気槽、２２…第２嫌気槽
３…好気槽
４…粗大気泡散気装置、４１…ディフューザ、４１ａ…送気筒、４１ｂ…空気流路、４１ｃ…クラウン、４１ｄ…気孔、４１ｅ…弁体、４２ａ…送気分岐管、４２ｂ…送気管、４３…送気元管、４４…自動開閉弁、４５粗大気泡
５…微細気泡散気装置、５１…散気板、５２…送気管
６…循環水管
７…整流板(嫌気槽)
７′…整流板(好気槽)
１０…沈殿池[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of a biological reaction tank for purifying sewage such as sewage and wastewater using anaerobic microorganisms and an agitation method thereof. More specifically, the oxygen state of sewage in an anaerobic tank or an anaerobic tank is appropriately set. The present invention belongs to the technical field of a bioreactor and a stirring method thereof that make it possible to stably stir sewage stably for a long time while maintaining the range.
[0002]
[Prior art]
The anaerobic-aerobic activated sludge process used to remove phosphorus in sewage, sewage and other sewage is a variation of the standard activated sludge process, which includes BOD (biochemical oxygen demand), simultaneous removal of phosphorus, and bulking This is a process that is effective in preventing (a phenomenon in which activated sludge expands and becomes difficult to settle due to the growth of filamentous bacteria). As such prior art, for example, “anaerobic sewage treatment method and apparatus” disclosed in JP-A-7-328688 and “biological reaction tank” disclosed in Japanese Patent No. 2998479 are known. It is.
[0003]
First, referring to FIG. 7 of the schematic cross-sectional view of the anaerobic sewage treatment apparatus, the conventional example 1 disclosed in Japanese Patent Application Laid-Open No. 7-328688 is referred to with the same name and the same reference numerals described in the same publication. In other words, the main body of the anaerobic sewage treatment apparatus 1 includes the treatment tank 2, and water to be treated such as domestic wastewater sent by a pump (not shown) flows into the treatment tank 2 from the manhole 3. And after processing with anaerobic microorganisms, it discharges from the outlet 4 opened to the upper cross section of the processing tank 2. FIG. The sludge accumulated in the treatment tank 2 is discharged from the upper part of the treatment tank 2 by suction with a bellows hose. An air diffuser 5 to which air is supplied from an air supply device 6 through an air supply pipe 7 is disposed below the treatment layer 2, and the inside of the tank is surrounded by the air released from the air diffuser 5. It is designed to be stirred.
[0004]
Air is supplied to the air diffuser 5 once every 30 to 120 minutes for 1 to 60 seconds. Such time varies depending on the size of the treatment tank 2, the quality of sewage, the amount of air supply, etc., but the removal rate of BOD, COD, and total nitrogen is increased to the extent that the anaerobic microorganisms are not inactivated. Is adjusted as appropriate. Also, if the amount of air is small, the agitation effect of sludge is not sufficient. On the other hand, if the amount of air is large, anaerobic treatment is not performed. Therefore, the amount of oxygen to be supplied is 0.5 to 10 g / m. ³ It is preferred that the minute.
[0005]
Next, conventional example 2 disclosed in Japanese Patent No. 2998479 is referred to with the same name and the same reference numerals described in the same publication with reference to FIG. The biological reaction tank 1 is composed of an anaerobic tank 2 and an aerobic tank 4, and a coarse bubble diffusing device having a plurality of pores with a diameter of 2 to 8 mm at a pitch of 100 to 1000 mm at the bottom of the anaerobic tank 2. 5 is disposed. Further, the microbubble diffuser plate 6 having 260 μm fine pores is disposed at the bottom of the aerobic tank 4. The coarse bubble diffusing device 5 is 0.7 m per tank. ³ Air volume per minute, and 0.4 m for the fine bubble diffuser 6 ³ A volume of air per minute is supplied.
[0006]
[Problems to be solved by the invention]
According to the “anaerobic sewage treatment method and apparatus” according to the above-described conventional example 1, or the “biological reaction tank” according to the above-described conventional example 2, since sewage can be purified, There are problems to be solved as described below.
[0007]
First, in the conventional example 1, 0.5 to 10 g / m in the treatment tank 2. ³ Minute amount of oxygen is supplied, but this amount of oxygen is 1.8-35.8 liters / m. ³ Corresponds to the amount of air in minutes (20 ° C.). According to the applicant's experiment, the air volume is 1.4 liters / m. ³ As a result, the range of air amount according to the conventional example 1 is not limited. Also Not appropriate. The air diffusion device 5 according to Conventional Example 1 is disposed at the bottom of the treatment tank 2, but the sewage cannot be sufficiently stirred depending on the shape of the tank.
[0008]
In the above-mentioned conventional example 2, the coarse bubble diffusing device 5 having a plurality of pores having a diameter of 2 to 8 mm at a pitch of 100 to 1000 mm is disposed at the bottom of the anaerobic tank 2. Since sewage flows back to the air diffuser 5, there is a possibility that air supply will be hindered and the sewage cannot be sufficiently stirred.
[0009]
Therefore, the present invention provides a biological reaction tank and a method for stirring the same that can sufficiently stir sewage stably for a long period of time while maintaining the oxygen state of sewage in an anaerobic tank or an anaerobic tank within an appropriate range. Is to provide.
[0010]
[Means for Solving the Problems]
The present invention has been made in view of the above circumstances, and therefore, in order to solve the above problems, the features of the means adopted by the biological reaction tank according to claim 1 of the present invention are an anaerobic tank or In the bioreaction tank that purifies the sewage such as sewage and drainage flowing into the anaerobic tank while stirring with the discharge of bubbles from the anaerobic tank or the aeration apparatus provided in the anoxic tank, The apparatus is composed of one or more air supply pipes arranged in the anaerobic tank or an oxygen-free tank, and a plurality of diffusers arranged at a predetermined pitch in each of the air supply pipes. Is The cylinder is connected to the air supply pipe and has an air flow path in the center, and is fitted over the upper part of the cylinder and has a plurality of pores in the outer periphery. Has an umbrella on the top The crown is accommodated in the upper part of the inner space of the crown, and is lifted by the inflow of air from the air flow path, and opens the upper opening of the air flow path that opens to the inner space side of the crown. From the block-shaped valve body that descends and shuts off the upper opening when air supply is stopped There is.
[0011]
The bioreactor according to claim 2 of the present invention is characterized in that the bioreactor according to claim 1 is characterized in that the air supply pipe is located on the inner wall side of the anaerobic tank or anaerobic tank. It is in a place where it is piped at a biased position.
[0012]
The bioreactor according to claim 3 of the present invention is characterized in that the bioreactor according to claim 2 is characterized in that the air supply pipe is disposed at a middle depth of the anaerobic tank or anoxic tank. In addition to being piped, a rectifying plate for circulating sewage between the one inner wall side and the other inner wall side is provided, separating the one inner wall side and the other inner wall side on the anaerobic tank or oxygen-free air pipe arrangement side. There is where it is done.
[0013]
The biological reaction tank according to claim 4 of the present invention Stirring method Features of the means adopted by In order to purify sewage such as sewage and drainage flowing into the anaerobic tank or anaerobic tank, coarse bubbles are intermittently discharged from the pores of the diffuser provided in the anaerobic tank or the anoxic tank. A method for stirring a biological reaction tank for stirring sewage, wherein when air is supplied from the air supply pipe to the diffuser, an air flow path leading from the air supply pipe to the pores is opened, and the plurality of pores are coarse. Air bubbles are released, and the discharged coarse air bubbles are spread outward along the lower surface of the umbrella portion above the pores, and the air flow path is shut off when the air supply is stopped. There is.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the biological reaction tank according to Embodiment 1 for carrying out the biological reaction tank stirring method of the present invention is schematically shown in FIG. 1 (a), which is a side sectional view, and an anaerobic tank viewed from the aerobic tank side. FIG. 1 (b) of the cross sectional view of FIG. 1, FIG. 1 (c) of the external view of the diffuser constituting the coarse bubble diffusing device, and FIG. 2 of the half sectional view of the diffuser showing the coarse bubble discharge state. Description will be made with reference to (a) and FIG. 2 (b) of the configuration explanatory diagram of the half section of the diffuser showing the air supply stop state.
[0015]
Reference numeral 1 shown in FIG. 1A is a biological reaction tank that purifies sewage such as sewage and wastewater with microorganisms. In this biological reaction tank 1, sewage such as sewage and drainage flows from a sedimentation basin 10. In addition, an anaerobic tank or an oxygen-free tank (hereinafter referred to as an anaerobic tank) 2 in which sludge is returned from a final sedimentation tank (not shown) and an aerobic tank 3 into which treated water treated in the anaerobic tank 2 flows. The sewage is purified by the anaerobic / aerobic activated sludge method. The anaerobic tank 2 has a depth that allows sewage within a depth of 6 m to flow in. As shown in FIG. 1 (b), a coarse bubble diffuser is located near the bottom of the anaerobic tank 2 and at a biased position on the inner wall side. A device 4 is provided. Thus, by arranging this coarse bubble diffusing device 4 at a biased position on the one inner wall side of the anaerobic tank 2, coarse bubbles rise from the one inner wall side of the anaerobic tank 2, so that the sewage on the one inner wall side Becomes an upward flow, becomes a horizontal flow near the water surface, and becomes a downward flow on the other wall side, so that the sewage is effectively stirred.
[0016]
The coarse bubble diffusing device 4 includes an air supply source pipe 43 piped on the upper part of the anaerobic tank 2, and an air supply branch pipe branched from the air supply source pipe 43 and piped along the inner wall of the anaerobic tank 2. Air is intermittently supplied through opening and closing of the automatic opening / closing valve 44 interposed near the branch portion of the air supply branch pipe 42a through 42a, and in the vicinity of the bottom surface of the anaerobic layer 2, parallel to the bottom surface. And a diffuser 41 that is disposed in the air supply pipe 42b at a predetermined pitch and that discharges coarse bubbles 45 into the sewage in the anaerobic tank 2. Note that air is supplied to the air supply source pipe 43 from a blower (not shown).
[0017]
The diffuser 41 has, for example, an outer shape as shown in FIG. size The air flow path is secured during the air supply, and the air flow path is blocked when the air supply is stopped. The sewage into the air supply pipe 42 when the air supply is stopped. It has a function to prevent backflow. As shown in FIGS. 2 (a) and 2 (b), a specific internal configuration of the diffuser 41 includes a feed cylinder 41a connected to the feed pipe 42b and having an air flow path 41b in the center, and the feed cylinder. It is fitted on the top of 41a and on the outer periphery. Multiple The upper opening of the air flow passage 41b which is accommodated in the upper portion of the inner space of the crown 41c and is lifted by the inflow of air from the air flow passage 41b and opens to the inner space side of the crown 41c. The block-shaped valve element 41e that opens when the air supply is stopped and blocks the upper opening is opened.
[0018]
Therefore, according to the diffuser 41, when air is supplied, the air flows between the air passage 41b, the upper opening of the air passage 41b, and the valve body 41e as shown by the broken line arrows in FIG. It flows into the internal space of the crown 41c through the gap, then flows out as a large bubble 45 from the pore 41d provided in the outer peripheral portion of the crown 41c, spreads outward along the lower surface of the umbrella portion of the crown 41c, and anaerobic It is discharged into the sewage in the tank 2 and rises. On the other hand, when the air supply is stopped, as shown by the solid line arrow in FIG. 2B, the sewage flows into the inner space of the crown 41c from the pore 41d, but the upper opening portion of the air flow path 41b by the valve body 41e. Is blocked and does not flow into the air flow path 41b, so that the inflow of sewage into the air supply pipe 42b is prevented.
[0019]
The aerobic tank 3 has a depth for allowing sewage within a depth of 6 m to flow in. Near the bottom of the aerobic tank 3, an air supply pipe 52 is disposed at a predetermined pitch in the air supply pipe 52. A fine bubble diffusing device 5 comprising a diffuser plate 51 that discharges fine bubbles over almost the entire area is disposed. Unlike the anaerobic tank 2, this aerobic tank 3 is required to promote the dissolution of oxygen and to maintain the dissolved oxygen in the aerobic tank 3 at 1.5 mg / liter or more. 51 is provided with a plurality of pores having a diameter of 150 to 400 μm for discharging fine bubbles. By releasing fine bubbles from the pores of the diffuser plate 51, the sewage can be stirred while promoting the dissolution of oxygen and maintaining the aerobic state of the sewage.
[0020]
Hereinafter, the operation mode of the biological reaction tank 1 according to the first embodiment will be described. From the pores 41 d of the diffuser 41 of each of the coarse bubble diffusing devices 4 to 1.0 to 3.0 in the sewage in the anaerobic tank 2. Liter / m ³ Minute air is discharged as coarse bubbles 45 for 5 minutes every 55 minutes. Since each of these diffusers 41 has a function of preventing the backflow of sewage into the air supply pipe 42b as described above, even when the air supply of air is stopped as in the biological reaction tank according to Conventional Example 2. The sewage does not flow back into the air supply pipe 42b.
[0021]
Therefore, according to the biological reaction tank 1 according to the first embodiment, the coarse bubbles 45 having low air dissolution efficiency can be discharged without any trouble, and the rising of the coarse bubbles 45 effectively removes the sewage in the anaerobic tank 2. Can be stirred. Moreover, since a small amount of air supply is sufficient as compared with Conventional Example 1, the anaerobic state of the sewage in the anaerobic tank 2 can be easily maintained. Incidentally, the DO (dissolved oxygen) of the sewage in the anaerobic tank 2 is about 0 mg / liter, and the ORP (oxidation-reduction potential) is -300 to -200 mV, confirming that the anaerobic state is maintained. did.
[0022]
In addition, as a problem of the anaerobic sewage treatment apparatus according to Conventional Example 1, the amount of air to be supplied is 1.8 to 35.8 liter / m. ³ Minute (20 ° C) is not always appropriate, 1.4 liters / m ³ Said that the minute is the appropriate amount of air. Nevertheless, in the biological reaction tank 1 according to the first embodiment, the range of the amount of air to be supplied is 1.0 to 3.0 liter / m. ³ Even if conditions such as the shape of the anaerobic tank 2 and the sludge mixing concentration in the anaerobic tank 2 are different, the sewage can be reliably and sufficiently stirred, and the growth of anaerobic microorganisms This is because the anaerobic state that does not hinder can be maintained reliably. Moreover, in the biological reaction tank 1 according to the first embodiment, air is released as coarse bubbles 45 for 5 minutes, for example, every 55 minutes, and this release time is also the shape of the anaerobic tank 2 and the anaerobic tank 2. Therefore, these times should be appropriately changed according to the conditions.
[0023]
By the way, the coarse bubble diffusing device 4 used as the stirring device is less expensive than the fine bubble diffusing device 5 and the sewage does not flow backward in the air supply pipe 42. Therefore, when the fine bubble diffusing device is used as the stirring device. In addition to being economically advantageous with respect to the manufacturing cost of the biological reaction tank, there is also an advantage that it is advantageous in terms of its maintenance and running costs.
[0024]
A biological reaction tank according to a second embodiment of the present invention will be described with reference to FIG. However, the biological reaction tank according to the second embodiment is different from the biological reaction tank according to the first embodiment in the presence or absence of a circulating water pipe. Components having the same function are denoted by the same reference numerals, and different points will be described.
[0025]
That is, the biological reaction tank 1 according to the second embodiment includes an anaerobic tank 2 and an aerobic tank 3 as in the first embodiment. The anaerobic tank 2 is configured to communicate with a circulating water pipe 6 for circulating a part of the treated water treated in the aerobic tank 3 from the aerobic tank 3.
[0026]
Therefore, according to the biological reaction tank 1 according to the second embodiment, the sewage is purified by the circulation type nitrification denitrification method, but as described above, only the circulation pipe 6 is added to the first embodiment. Similarly to the biological reaction tank according to the first embodiment, the biological reaction tank according to the second embodiment has an effect that the oxygen state in the anaerobic tank 2 can be stirred while being maintained in an appropriate range.
[0027]
A biological reaction tank according to Embodiment 3 of the present invention will be described with reference to FIG. However, the difference between the biological reaction tank according to the third embodiment and the biological reaction tank according to the first embodiment is in the structure of the tank and the presence or absence of the circulating water pipe, and other than that, the structure is the same. The same reference numerals are assigned to the same components and the components having the same functions, and different points will be described.
[0028]
That is, the biological reaction tank 1 according to the third embodiment includes the anaerobic tank 2 and the aerobic tank 3 as in the first embodiment. The anaerobic tank 2 has a depth for allowing sewage to flow within a depth of 6 m, and is provided with a coarse bubble diffusing device 4 in the vicinity of the bottom of the anaerobic tank 2 at a biased position on the inner wall side. Sewage such as sewage and drainage primarily treated from the pond flows in, and a first anaerobic tank 21 to which sludge is returned from a final sedimentation tank (not shown) and treated water treated in the first anaerobic tank 21 flow in. It consists of the second anaerobic tank 22. A circulation water pipe 6 for circulating a part of the treated water treated in the aerobic tank 3 communicates with the second anaerobic tank 22 from the aerobic tank 3.
[0029]
Therefore, according to the biological reaction tank 1 according to the third embodiment, the sewage is purified by the anaerobic / anoxic / aerobic method. As described above, the anaerobic tank 2 includes the first anaerobic tank 21 and the second anaerobic tank 21. The present embodiment is in the point divided into an anaerobic tank 22 and the point where the circulating water pipe 6 is provided, and the other configuration is the same as that of the biological reaction tank according to the first embodiment. Similar to the biological reaction tank according to the first embodiment, the biological reaction tank according to No. 3 has an effect of being able to stir while maintaining the oxygen state in the anaerobic tank 2 within an appropriate range.
[0030]
FIG. 5 (a) schematically shows a side view of a two-stage structure of a biological reaction tank according to Embodiment 4 of the present invention, and FIG. 5 (a) shows a side sectional view of a three-stage structure schematically shown. This will be described with reference to b). However, the difference between the biological reaction tank according to the fourth embodiment and the biological reaction tank according to the first embodiment is in the structure of the tank and the presence or absence of the circulating water pipe, and the other configuration is the same. The same reference numerals are assigned to the same components and the components having the same functions, and different points will be described.
[0031]
In the fourth embodiment, sewage is purified by a step-inflow multi-stage denitrification method, and the biological reaction tank 1 shown in FIG. 5 (a) is a front stage composed of an anaerobic tank 2 and an aerobic tank 3. It is provided on the downstream side of the part and the front part, and is configured in a two-stage structure of the rear part composed of the anaerobic tank 2 and the aerobic tank 3. A circulating water pipe 6 for circulating a part of the treated water purified in the aerobic tank 3 is communicated with the anaerobic tank 2 in the rear part from the aerobic tank 3 in the rear part.
[0032]
The biological reaction tank 1 shown in FIG. 5 (b) is provided in a front stage part composed of an anaerobic tank 2 and an aerobic tank 3, and a middle stage composed of the anaerobic tank 2 and the aerobic tank 3. It is provided on the downstream side of the part and the middle part, and is configured in a three-stage structure of a rear part composed of the anaerobic tank 2 and the aerobic tank 3. A circulating water pipe 6 for circulating a part of the treated water purified in the aerobic tank 3 is communicated with the anaerobic tank 2 in the rear part from the aerobic tank 3 in the rear part.
[0033]
According to the biological reaction tank 1 according to the fourth embodiment, the anaerobic tanks 2 and the aerobic tanks 3 are alternately arranged, and the aerobic tank 2 is changed from the aerobic tank 3 in the rear stage portion to the anaerobic tank 2. Since only the circulating water pipe 6 that circulates a part of the treated water purified in 3 is communicated, the biological reaction tank 1 according to the fourth embodiment is the same as the biological reaction tank 1 according to the first embodiment. In addition, there is an effect that stirring can be performed while maintaining the oxygen state in the anaerobic tank 2 within an appropriate range.
[0034]
FIG. 6 (a) of the side cross-sectional view schematically showing the biological reaction tank according to Embodiment 5 of the present invention, and FIG. 6 (b) of the cross-sectional view of the anaerobic tank viewed from the aerobic tank side. Will be described with reference to FIG. However, the difference between the biological reaction tank according to the fifth embodiment and the biological reaction tank according to the first embodiment is the difference in depth between the anaerobic tank and the aerobic tank. Because there is the same thing In addition, the same reference numerals are given to those having the same function.
[0035]
Reference numeral 1 shown in FIG. 6A is a biological reaction tank, and this biological reaction tank 1 is composed of an anaerobic tank 2 and an aerobic tank 3 into which treated water treated in the anaerobic tank 2 flows. The anaerobic tank 2 and the aerobic tank 3 are both deeper than a water depth of 6 m. As shown in FIG. 6 (b), an air supply pipe 42b arranged in parallel with the bottom surface at a position intermediate in the depth of water in the anaerobic tank 2 and at an offset position on the inner wall side of the anaerobic tank 2, and a predetermined amount in the air supply pipe 42b. A coarse bubble diffusing device 4 comprising a diffuser 41 arranged at a pitch of 1 is provided. Furthermore, the inner wall side and the other inner wall side on the coarse bubble diffusing device 4 are separated from each other and extend to a position above the coarse bubble diffusing device 4 and to a lower position near the bottom of the anaerobic tank 2. A rectifying plate 7 is provided.
[0036]
Even if the coarse bubble diffusing device 4 is disposed in the middle of the water depth by the function of the rectifying plate 7, when the upward flow of sewage generated by the discharge of the coarse bubbles 45 exceeds the upper end of the rectifying plate 7. Since it becomes a downward flow and flows between the lower end of the rectifying plate 7 and the bottom surface of the anaerobic tank 2 and convects as an upward flow, the entire sewage in the anaerobic tank 2 is effectively stirred.
[0037]
The water depth of the aerobic tank 3 is a depth exceeding 6 m as described above. Like the anaerobic tank 2, the water depth is in the middle position of the water depth and at a position offset on the inner wall side in parallel with the bottom surface. A fine bubble diffusing device 4 is provided which includes an air supply pipe 52 arranged and a gas diffusion plate 51 which is arranged in the air supply pipe 52 at a predetermined pitch and discharges fine bubbles. Further, the one inner wall side and the other inner wall side on the side where the fine bubble diffusing device 5 is arranged are separated to extend to a position above the fine bubble diffusing device 5 and to a lower position near the bottom of the aerobic tank 3. An extending rectifying plate 7 'is disposed. Also in the aerobic tank 3, as in the anaerobic tank 2, the entire sewage in the aerobic tank 3 is effectively stirred and maintained in an aerobic state within an appropriate range by the action of the rectifying plate 7 ′.
[0038]
According to the biological reaction tank 1 according to the fifth embodiment, the depth of the anaerobic tank 2 and the aerobic tank 3 is different from that of the biological reaction tank according to the first embodiment, and the function of the current plate 7 Thus, since the sewage in the anaerobic tank 2 can be effectively convected and stirred, the same effect as the biological reaction tank according to the first embodiment can be obtained. Further, in addition to this effect, the coarse bubble diffusing device 4 is disposed at a shallow position in the middle of the water depth even though the water depth of the anaerobic tank 2 is deep, and the air supply pressure can be lowered. . That is, since the power energy of the blower can be reduced, it is possible to contribute to the reduction of the running cost of the biological reaction tank 1.
[0039]
By the way, in the biological reaction tank 1 which concerns on this Embodiment 5, the structure which consists of the anaerobic tank 2 and the aerobic tank 3 which purify | clean-process wastewater by the anaerobic / aerobic activated sludge method shown to Fig.1 (a). Although the case has been described as an example, the anaerobic tank 2 and the aerobic tank 3 are applied to a biological reaction tank having any arrangement shown in FIGS. 3 to 5 (a) and 5 (b). The technical idea of the biological reaction tank 1 according to Embodiment 5 can be applied, and the coarse bubble diffusing device 5 and the shielding plate 7 are also provided to the anaerobic tank 2 having a water depth of 6 m or less. Thus, the intended purpose of effectively stirring the sewage can be achieved, and the water depth of the anaerobic tank 2 is not limited.
[0040]
【The invention's effect】
As described above, claims 1 to 5 of the present invention. 3 Or a biological reaction tank according to the present invention 4 According to the agitation method of the biological reaction tank according to the present invention, the diffuser provided in the anaerobic tank or the oxygen-free tank has a function of preventing the backflow of sewage into the air supply pipe, and the biological reaction tank according to Conventional Example 2 In this way, even when the air supply is stopped, the sewage does not flow back into the air supply pipe, so that coarse bubbles with low air dissolution efficiency can be released without any trouble. Can be convected and stirred effectively. Moreover, since the amount of air is smaller than in the case of the anaerobic sewage treatment apparatus according to Conventional Example 1, there is an excellent effect that the anaerobic state of the sewage in the anaerobic tank can be easily maintained.
[0041]
Further, claims 1 to 5 of the present invention. 3 According to the biological reaction tank according to the above, the coarse bubble diffusing device used as the stirring device is less expensive than the fine bubble diffusing device. Therefore, in addition to being economically advantageous with respect to the manufacturing cost of the biological reaction tank as compared with the case where a fine bubble diffuser is used as the stirring device, there is also an effect that it is advantageous with respect to its maintenance management cost and running cost. .
[0042]
Further claims of the present invention To 3 According to such a biological reaction tank, a diffuser is disposed in an air supply pipe disposed at a depth intermediate position of an anaerobic tank or an oxygen-free tank, and the inner wall side of the anaerobic tank or an oxygen-free air supply pipe is disposed on the other side. Since the current plate that separates the inner wall side is provided, in addition to the above effects, the air supply pressure can be reduced and the power energy for supplying air can be reduced. It can contribute to the reduction of the running cost of the biological reaction tank.
[Brief description of the drawings]
FIG. 1 relates to Embodiment 1 of the present invention, FIG. 1 (a) is a side sectional view of a biological reaction tank schematically shown, and FIG. 1 (b) is a transverse section of an anaerobic tank viewed from the aerobic tank side. FIG. 1 and FIG. 1C are external views of a diffuser constituting the coarse bubble diffusing device.
FIG. 2 (a) relates to the first embodiment of the present invention, FIG. 2 (a) is a half sectional view of the diffuser showing the coarse bubble discharge state, and FIG. 2 (b) is an illustration of the diffuser showing the air supply stop state. FIG.
FIG. 3 is a side cross-sectional view of a biological reaction tank schematically shown in the second embodiment of the present invention.
FIG. 4 is a side cross-sectional view of a biological reaction tank schematically shown in Embodiment 3 of the present invention.
FIG. 5 is a side sectional view of a two-stage biological reaction tank schematically shown in FIG. 5 (a), and FIG. 5 (b) is a three-stage schematic shown in FIG. It is side surface sectional drawing of a biological reaction tank.
6 (a) is a side sectional view of a biological reaction tank schematically shown in FIG. 6 (b), and FIG. 6 (b) is a cross sectional view of an anaerobic tank as viewed from the aerobic tank side. FIG.
7 is a schematic cross-sectional view of an anaerobic sewage treatment apparatus according to Conventional Example 1. FIG.
FIG. 8 is a schematic configuration explanatory diagram of a biological reaction tank according to Conventional Example 2.
[Explanation of symbols]
1 ... Bioreaction tank
2 ... Anaerobic tank or oxygen-free tank, 21 ... First anaerobic tank, 22 ... Second anaerobic tank
3 ... Aerobic tank
4 ... Coarse bubble diffuser, 41 ... Diffuser, 41a ... Cylinder, 41b ... Air flow path, 41c ... Crown, 41d ... Pore, 41e ... Valve element, 42a ... Air supply branch pipe, 42b ... Air supply pipe, 43 ... Air supply source pipe, 44 ... Automatic open / close valve, 45 coarse bubbles
5 ... Fine air bubble diffuser, 51 ... Air diffuser, 52 ... Air pipe
6 ... Circulating water pipe
7 ... Rectifying plate (anaerobic tank)
7 '... Rectifying plate (aerobic tank)
10 ... sedimentation pond

Claims

In a biological reaction tank that purifies sewage such as sewage and drainage flowing into an anaerobic tank or an anaerobic tank while stirring by releasing air bubbles from an air diffuser provided in the anaerobic tank or anaerobic tank, The air diffuser is composed of one or more air supply pipes arranged in the anaerobic tank or anoxic tank, and a plurality of diffusers arranged at a predetermined pitch in each of these air supply pipes. The diffuser is connected to the air supply pipe and has a gas supply cylinder having an air flow path in the center, and is fitted over the upper part of the gas supply cylinder, has a plurality of pores in the outer peripheral part, and has an umbrella part in the upper part The crown is accommodated in the upper part of the inner space of the crown, and is lifted by the inflow of air from the air flow path, and opens the upper opening of the air flow path that opens to the inner space side of the crown. Sending Bioreactor, characterized by comprising a block-shaped valve body that blocks the upper opening is lowered at the time of stop.

The biological reaction tank according to claim 1, wherein the air supply pipe is piped at a biased position on the inner wall side of the anaerobic tank or anoxic tank.

The air supply pipe is piped at a water depth intermediate position of the anaerobic tank or anaerobic tank, and one inner wall side is separated from one inner wall side and the other inner wall side on the anaerobic tank or anaerobic air supply pipe arrangement side. The biological reaction tank according to claim 2, wherein a rectifying plate for circulating sewage is disposed between the inner wall and the other inner wall side.

In order to purify sewage such as sewage and wastewater flowing into an anaerobic tank or an anaerobic tank, coarse air bubbles are intermittently discharged from pores of a diffuser provided in the anaerobic tank or an anaerobic tank, and the sewage is discharged. A stirring method for a bioreactor tank, wherein when air is supplied from the air supply pipe to the diffuser, coarse air bubbles are removed from the plurality of air holes by opening an air flow path leading from the air supply pipe to the air holes. The agitation of the bioreaction tank is characterized in that the discharged coarse bubbles are spread outward along the lower surface of the umbrella portion above the pores, and the air flow path is shut off when the air supply is stopped. Method.